Effect of Strain Rate on Deformation Behavior in α+β Phase Field of Titanium Alloy TC11

The hot deformation behavior of titanium alloy TC11 in the temperature from 780 ℃ to 990 ℃,strain rate from 0.001 s-1 to 70 s-1 were studied using isothermal constant strain rate compressing testing on hot simulator.The characteristic of stress-strain curves was obtained,and the effect of strain rate on microstructure was analyzed.The results show that the flow stress of the titanium alloy TC11 is sensitive to deformation temperature.The flow stress curves exhibit flow softening at higher strain rate and lower deformation temperature,while a steady-state behavior appears at higher deformation temperature and lower strain rate.When strain rate is higher than 10 s-1 and the temperature range is 780～870 ℃,the material exhibits flow instabilities such as adiabatic bands or flow localization.When strain rate is about 0.001 s-1 and the temperature range is 870 ～960 ℃,the material exhibits superplastic deformation.When the hot deformation parameter is 0.001 s-1 and 990 ℃,the materials exhibit large-grained superplasticity.